This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
3GPP third generation partnership project
BCCH broadcast control channel
BSC base station controller
BSIC base station identity code
BSS base station subsystem
BTS base transceiver station
DL downlink (BTS/eNB towards UE)
EDGE enhanced data rates for GSM evolution
eNB EUTRAN Node B (evolved Node B, a base station/access node)
E-UTRAN evolved UMTS radio access network (also termed LTE/3.9G)
FDD frequency division duplex
GERAN GSM/EDGE radio access network (also known as 2.5G)
GSM global system for mobile communications
ID identity
LTE long term evolution
MS mobile station (also termed UE)
NB node B (a base station/access node)
PCID physical layer cell ID
RAT radio access technology
RSRP reference signal received power
RSRQ reference signal received quality
SC-FDMA single carrier, frequency division multiple access
TDD time division duplex
TTI transmission time interval
UE user equipment (also termed MS)
UL uplink (UE towards eNB)
UMTS universal mobile telecommunication system
UTRAN UMTS radio access network (also known as 3G)
A communication system known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA) is currently under development within the 3GPP. As presently specified the DL access technique will be orthogonal frequency division multiple access (OFDMA), and the UL access technique will be single carrier, frequency division multiple access (SC-FDMA).
One specification of interest is 3GPP TS 36.300, V8.6.0 (2008-09), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (E-UTRAN); Overall description; Stage 2 (Release 8), incorporated by reference herein in its entirety.
FIG. 1 is a schematic diagram of a mobile station MS under control of a base transceiver station BTS of a GERAN system over an Um link. In the GERAN system the BTSs are under control of a base station controller BSC which communicates with the GSM/UMTS core network via at least the Gb and A interfaces as shown. Also at FIG. 1 there are shown six neighbor access nodes, some of which are GERAN BTSs, some of which are UTRAN NBs and some of which are E-UTRAN eNBs. The MS measures the serving GERAN BTS with which it has the Um interface and also measures the neighbor access nodes of whatever radio access technology RAT the MS is compatible, and sends to the serving BTS a measurement report. Similarly, the MS may instead be under control of the UTRAN network and send its measurement reports of its serving UTRAN NB and also of the neighboring GERAN BTSs and E-UTRAN eNBs to the serving NB of the UTRAN network. Either of these inter-RAT measurement reports is an exemplary but non-limiting environment for embodiments of these teachings
With the adoption of E-UTRAN as a new radio technology RAT, there is a need to develop inter-working between pre-existing RATs to enable mobile terminals to operate within both legacy and E-UTRAN infrastructure systems such as the environment depicted at FIG. 1 and the measurement reporting of neighbor cells by a user equipment UE (shown in FIG. 1 as the MS). Measurement Reporting for E-UTRAN cells identifies an important aspect for GERAN/E-UTRAN interworking, subject to be standardized in 3GPP Release 8.
Due to the agreement at GERAN #38bis (see Exhibit A attached to the priority document U.S. Provisional Patent Application No. 61/198,859, filed Nov. 10, 2008): document G2-080368 entitled MEASUREMENT REPORTING FOR GERAN/E-UTRAN INTER-WORKING; 3GPP TSG GERAN2#38bis, Xi'an, China; Jun. 24-27, 2008; by Nokia Corporation & Nokia Siemens Networks) to employ the approach of a black list for E-UTRAN neighbor cells, (see particularly Section 3 of that document which states that only neighbor cells are signaled which should not be considered as handover or cell reselection candidate), the ID's of allowed cells are not explicitly broadcasted and hence the mobile unit cannot simply index a cell in the measurement report, as is possible in the white list approach used for state-of-the-art neighbor cell reporting for GERAN or UTRAN cells.
This means that the full physical layer cell identity (PCID) of the E-UTRAN cell needs to be included in the measurement report. This is seen to reduce the efficiency of neighbor cell measurement reporting for E-UTRAN cells. Regardless of whether this black list approach will be more or less efficient in practice, it is the agreed framework for moving forward for inter-RAT measurement reporting. Consequently, the design of new measurement reporting messages is necessary to obtain the best reporting efficiency.
In order to keep impact of the introduction of E-UTRAN low on the mobile terminals, GERAN is envisaging to reuse legacy measurement report message formats, such as MEASUREMENT REPORT or ENHANCED MEASUREMENT REPORT in the dedicated mode or dual transfer mode; and PACKET MEASUREMENT REPORT or PACKET ENHANCED MEASUREMENT REPORT in the packet transfer mode also in the case of GERAN to E-UTRAN interworking.
By the reuse of existing measurement report message formats, restrictions on the reporting itself are naturally imposed in order to fit into these pre-existing formats. In particular, the ID of an E-UTRAN cell is represented by the PCID, requiring 9 bits which is 3 bits more than used for the BSIC identity in GERAN. Consequently the measurement reporting quantity of 6 bits as used for reporting on GERAN or UTRAN cells needs to be truncated to 3 bits to allow for this approach when reporting on the E-UTRAN cells. Further detail in this regard may be seen at section 4 of the above document G2-080368 and in sections 2.4 and 3 in the document G2-080510 entitled ENHANCED MEASUREMENT REPORTING FOR LTE; 3GPP TSG GERAN2#39bis, Sophia-Antipolis, France, Sep. 30-Oct. 3, 2008; by Nokia Corporation & Nokia Siemens Networks).
The reduced granularity of the reporting quantity is currently under discussion in 3GPP between GERAN and RAN 4; the reporting quality can only be three bits. See Exhibit B attached to the above referenced priority document: document TSGG #38 (08)1347 entitled LS ON REPORTING E-UTRAN MEASUREMENTS; 3GPP TSG GERAN Meeting No. 39, Florence, Italy; 25-29 Aug. 2008), where the reporting quantity may be either RSRP (Reference Signal Received Power) or RSRQ (Reference Signal Received Quality).
A contribution to GERAN has provided a basic solution for employing a reduced 3 bit granularity reporting for E-UTRAN cells. See Exhibit C attached to the above referenced priority document: document GP-081159 entitled ON MEASUREMENT REPORTING FOR GERAN/E-UTRAN INTERWORKING; 3GPP TSG GRAN #39, Florence, Italy; 25-29 Aug. 2008; by Nokia Siemens Networks & Nokia Corporation. One principle of the proposed encoding of the 3 bit measurement quantity is provided in FIG. 1 of document GP-081159, which is reproduced herein as FIG. 2.